# Ohm's Law

Ohm’s Law states that the current I in a conductor and the voltage V between the ends of the conductor are directly proportional. The formula VRI is a mathematical representation of this law. Ohm’s law can be used to calculate the three basic quantities of a circuit if at least two of them are known. The three basic quantities are voltage, current, and resistance. The physicist Georg Simon Ohm established and proved the relationship between voltage, current, and resistance. Ohm’s law was named after him.

It is important to understand that Ohm’s Law only applies to ohmic resistors. These include normal resistors and devices that have a linear relationship between voltage and current. The resistance of a diode or a lamp cannot be calculated using Ohm’s Law because the current and voltage of these components do not have a linear relationship. Normal resistors always have the same value within their limits, independent of voltage and current. This is the only resistance value that can be calculated with Ohm’s Law. To simplify the calculation, we have expanded the "Online Calculator" area for you with the formulas listed below:

Measuring Units:

Voltage          V = Volt [V]
Current           I = Ampere [A]
Resistance    R = Ohm [Ω]